In surface mount technology, a bead of solder, typically tin/lead with a resin flux, is applied to a screen/stencil as a continuous bead line which bead line is subsequently squeegeed onto the board in a separate operation. Applying a uniform, homogeneous, continuous bead is difficult because of the high viscosity of the solder. Also, the solder tends to separate if stored for any length of time. Cartridges are available to dispense the solder, such as with a caulking gun. Most users prefer to buy the solder paste in jars containing 100 g, 250 g, 500 g or 1000 g and then simply mix the solder prior to use.
Broadly the invention comprises a solder paste applicator which cooperates with both a mixing assembly and a plunger assembly. The applicator has a dispensing end and an acquisition/mixing end. The acquisition/mixing end is used to mix solder in the container in which it is sold and to transfer the solder from the container to the applicator. The dispensing end applies a uniform bead of solder. If the solder in the applicator is homogeneous then the plunger assembly is used to dispense the solder. If the solder in the applicator is not homogeneous then the mixing assembly is first used and then the plunger assembly is used.
The invention broadly comprises an applicator having a tubular section and a trough section. The tubular section terminates in a dispensing tip at one end of the applicator and the trough section terminates in a scoop at the other end of the applicator. A collar is slideably received over the applicator where the tubular section and trough section are joined.
The mixing assembly is received in the tubular section and reciprocated to mix the solder. The plunger assembly is received in the tubular section and a plunger extrudes the solder from the dispensing tip. The solder is dispensed as a uniform, homogeneous bead onto a screen/stencil. Thus, the prior art problems of a homogeneous solder dispensed in a uniform bead are overcome in a simple and expedient manner.